SEA-FISHEKIES LABORATORY. 215 



progressive increase in the numbers of Oithona similis 



during the three years is noteworthy. 



The greatest single hauls of Copepoda (taken with the 



ordinary " coarse " net) in Port Erin Bay, during 1911, 



were as follows : — 



Species. 

 Oithona similis 



Pseudocalanus elongatus 



Paracalanus parvus 



Acartia clausi 



Temora longicornis 



Calanus helgolandicus .. 



umber. 



Date 





214,000 



July 



18 



73,200 



f3 



21 



68,000 



Aug. 



3 



51.300 



}> 



24 



46,500 



July 



31 



34,350 



Aug. 



24 



61,300 



»> 



24 



32,300 



Sept. 



29 



59,000 



Aug. 



24 



42,100 



Oct. 



19 



17,000 



June 



3 



17,000 



July 



4 



1,800 



,, 



18 



Some of these are very large hauls indeed for 

 Copepoda. 



If we arrange all the species of Copepoda (15) 

 recorded on our forms in 1911 in two series, according 

 as they are supposed to be " Oceanic " or " Neritic," we 

 get the following result : — 



Oceanic. 



Calanus helgolandicus. 

 Pseudocalanus elongatu 

 Oithona similis. 

 Paracalanus parvus. 

 [Acartia clausi] 

 A nomalocera patersoni. 

 Microcalanus pusillus. 

 Metridia lucens. 

 Candacia arrnata. 



Neritic. 



Temora longicornis. 

 [Centropages hamatus] 

 Euterpina acutifrons. 

 Isias clavipes. 

 Parapontella brevicomis. 

 Labidocera wollastoni. 



A few of these are undoubtedly oceanic and neritic 

 respectively, for example Calanus lielgolandicvs is 

 typically oceanic, while Isias clavipes is a shore form; 

 but other cases are more doubtful. One would expect an 

 oceanic form which only invades a shore area on 

 occasions to have a more or less periodic distribution, but 



p 



